原生js :removeClass和addClass

 function removeClass(obj, aClass) {
     var re = new RegExp('\\b' + aClass + '\\b');
     if (obj.className != '') {

         if (re.test(obj.className)) {
             var arr = obj.className.split(' ');
             for (var i = 0; i < arr.length; i++) {
                 if (arr[0] == aClass && arr[arr.length - 1] == aClass) {
                     obj.className = '';
                 } else if (arr[i] == aClass) {
                     arr.splice(i, 1);
                     obj.className = arr.join(' ');

                 }
             }
         } else {
             return;
         }
     }
     removeClass(obj, aClass);
 }

removeClass

 addClass = function (obj, aClass) {
     var re = new RegExp('\\b' + aClass + '\\b');

     if (obj.className) {
         if (!re.test(obj.className)) {
             obj.className += ' ' + aClass;
         }
     } else {
         obj.className = aClass;
     }
     return this;
 }

addClass

 function removeClass(obj, aClass) {
     var re = new RegExp('\\b' + aClass + '\\b');
     if (obj.className != '') {
         if (re.test(obj.className)) {
             var arr = obj.className.split(' ');
             for (var i = 0; i < arr.length; i++) {
                 if (arr[0] == aClass && arr[arr.length - 1] == aClass) {
                     obj.className = '';
                 } else if (arr[i] == aClass) {
                     arr.splice(i, 1);
                     obj.className = arr.join(' ');
                 }
             }
         }
     }
 }

removeClass